It wouldn't have been too much trouble, but it wouldn't have made sense with the scenes that actually were aligned with Bane's dialogue during that montage. Imo, a shot of Selina walking out wouldn't fit.

I disagree, Nolan could have quite easily made it work.
Just one example, Bane says "This city...", cut to Selina walking away from the ravaging mob of prisoners, cut to Bane saying "it will endure", cut to the bomb in the truck.

It would have shown a contrast between Selina and the rest of the prisoners and would have looked damn cool to beat. It's not a big beef by any means, but I think he should have included it somewhere.

What is a slightly bigger beef is that all we see of prison Selina is about 20 seconds, and only when she's coming in and when she's about to be freed. It almost seems like Nolan just wanted to get rid of her for a while and stuck her in a cell. As someone else mentioned in some other thread, once Bruce got broken the Gotham segment of the movie should have focused on Selina. But oh well.